Dobbies for weaving looms

ABSTRACT

In a dobby for a weaving loom each heald frame is vertically reciprocable by movement of a respective linkage moved by a respective rotatable shedding cam. A continuously rotating electric motor drives the shedding cam through a clutch when the clutch is engaged, but the cam ceases to be rotated and the heald frame halts when the clutch is disengaged. The clutches are engaged in a predetermined sequence to give a desired shedding motion in response to programmed engage clutch instructions in a program read by a program reader in a electrical circuit controlling engagement and disengagement of the clutches. When a clutch is engaged the heald frame is either raised or lowered and when it reaches either of its fully raised or fully lowered positions the linkage operates a switch to disengage the clutch so as to halt the heald frame at the raised or lowered position until the next engage clutch instruction is received to move the frame.

United States Patent [72] Inventor [2 l 1 Appl. No. [22] Filed [45] Patented [73] Assignee [32] Priority 1 1 [54] DOBBIES FOR WEAVING LOOMS 3,191,633 6/1965 Piot l39/5SX 3,192,957 7/1965 ONeill 139/55 FOREIGN PATENTS 277,045 7/1914 Germany 139/79 323,522 12/1934 ltaly 139/55 Primary ExaminerJames Kee Chi Attorney-Norris and Bateman ABSTRACT: In a dobby for a weaving loom each heald frame is vertically reciprocable by movement of a respective linkage moved by a respective rotatable shedding cam. A continuously rotating electric motor drives the shedding cam through a clutch when the clutch is engaged, but the cam ceases to be rotated and the heald frame halts when the clutch is disengaged. The clutches are engaged in a predetermined sequence to give a desired shedding motion in response to programmed engage clutch instructions in a program read by a program reader in a electrical circuit controlling engagement and disengagement of the clutches. When a clutch is engaged the heald frame is either raised or lowered and when it reaches either of its fully raised or fully lowered positions the linkage operates a switch to disengage the clutch so as to halt the heald frame at the raised or lowered position until the next engage clutch instruction is received to move the frame.

PATENIEDJANZBIHTI 3557.842

sum 1 or 3 #vvENToe Ian Stephen Potter by wouibq PATENTEnJmeslsn SHEET 3 OF 3 3.551842 INVE P Ian Stephen Porter b UMvQJaU/un/vs DOBBIES FOR WEAVING LOOMS BACKGROUND OF THE INVENTION This invention relates to improvements in dobbies for weaving looms.

In some known dobbies reciprocating knives are used as part of the mechanism for carrying out the shedding motion, the lifting of particular healds in a particular sequence being controlled by program means in which the programmed instructions are in the form of a pattem such as a pattern of holes in a chain of punched cards or an arrangement of pegs in a chain of pegs. Hitherto dobbies controlled by program means could not be used for heavy work because of the strain placed upon the knives, and dobbies controlled by shedding cams acting on the healds through tappet levers, rack and pinions and heald frames, as in an ordinary loom, have been used instead when heavy lifting was involved. However, the provision of intricately shaped shedding cams has proved expensive particularly as the set of shedding cams can only be used in the weaving of one particular design.

SUMMARY OF THE INVENTION One object of the invention is the provision of a dobby which can carry out heavy lifting work during shedding but is controlled by program means.

According to the invention a dobby for a weaving loom comprises a plurality of raisable and lowerable heald frames mounted on the loom; each heald frame having a movable linkage connected thereto, said linkage being in contact with a rotatable shedding cam shaped to move the linkage to raise and lower the heald frame once per revolution of the shedding cam, said shedding cam being affixedly mounted on rotatable driving torque transmission means connected to a source of rotary motion, engageable and disengageable clutch means being provided in the transmission means, whereby drive to the shedding cam is transmitted thereto from the source of rotary motion through the clutch means when the latter is engaged and whereby the drive is interrupted when the clutch is disengaged, engagement of the clutch means being controlled by electrical means provided with program reading means for reading engage clutch instructions supplied thereto by program means, the heald frame being movable by rotation of the shedding cam during engagement of the clutch means in response to an engage clutch instruction from the program means, and disengagement of the clutch means being also controllable by the electrical means wherein there is means opera- DESCRIPTION OF THE DRAWINGS AND PREFERRED EMBODIMENTS In order that the nature of the invention may be more fully understood it will now be described with reference to the accompanying drawings in which:

FIG. 1 is a fragmentary diagrammatic representation of a weaving loom with a dobby formed according to the invention in which the arrangement comprising a pair of shedding cams on the right-hand side of the drawing is a section on the line l-I in FIG. 3;

FIG. 2 is a diagrammatic representation of a selector unit and alternative form of program means to that shown in FIG.

FIG. 3 is a plan view on the line III-III of the shedding cam arrangement on the right-hand side of the loom in FIG. 1; and

FIG. 4 is a diagram of electrical circuit for putting the invention into practice.

Referring to FIG. I a loom frame 2 is provided with a plurality of heald shafts or heald frames disposed one behind the other and of which only one is shown at 4. Each heald frame carries a pair of staves 6 supporting a plurality of healds 8, and

each frame has mounted thereon an individual substantially vertical heald rack 10 slidably passing through a top of the loom frame to mesh with a rotatable pinion 12 (mounted by means not shown) on the top of the frame 2. Another portion of the pinion meshes with a substantially horizontal rack bar 14 slidably supported in a runway 15 mounted on top of the loom frame. This rack bar is pivotally connected to one end of a linkage l6 pivotally connected at its other end to an upper end of a tappet lever a pivotally mounted at 18 on the loom frames. A lower end of the tappet lever a is provided with a rotatable cam follower 20 located in a cam track 22 in a side of rotatable, positive shedding cam b keyed to a rotatable output shaft 0 from a high reduction gearbox d. The profile of the track 22 is arranged such that during one complete revolution of the cam b the tappet lever is oscillated according the double-headed arrow w, thereby reciprocating the rack bar 14 as indicated by the double-headed arrow 1:. This horizontal reciprocation is converted by the pinion l2 and heald rack 10 into vertical reciprocation and results in the heald frame 4 being raised and lowered in guides 24 once during the complete revolution of the camb.

Referring to FIGS. 1 and 3 the gearbox d, which is mounted on the loom frame, is driven by a rotatable input shaft 2 provided at one end with an electromagnetic clutch j driven by a rotatable output shaft g from an electric motor it, also mounted on the loom frame. This clutch can be engaged and disengaged (by means described below) and when engaged the rotary motion of the shaft is transmitted through the clutch to the input shafts e of the gearbox d to rotate the cam 12, but when disengaged the drive to the shaft e e is inter rupted and the drive to the cam is therefore stopped. On the opposite side of the motor h to the shaft g is another output shaft 3 from the motor. This second output shaft is connected to an electromagnetic clutch j capable; when engaged, of transmitting drive to a gearbox d driving a cam b similar to the cam b. When cam b is rotated it oscillates a tappet lever a which through another rack and pinion arrangement (not shown) can reciprocate another heald frame (not shown). Another electric motor h is arranged to drive a further pair of shedding cams b, b through clutches f, f and high reduction gearboxes d", d. Cams b b can oscillate tappet levers a a arranged to reciprocate a further pair of heald frames (not shown). On the left-hand side of the loom in FIG. 1 four more shedding cams (not shown) are mounted and are arranged to oscillate another four tappet levers reciprocating a further four heald frames (not shown). These other four cams are driven by a pair of electric motors through a transmission arrangement similar to that described for the cams b 1 1 b and b. It follows therefore that in the loom described herein there are eight heald frames reciprocated by eight cams driven by four motors through a transmission system comprising eight clutches and eight gearboxes.

When the dobby is in operation the electric motors continuously rotate their pairs of output shafts but a particular heald frame can only be raised or lowered when the particular shedding cam acting on that heald frame is rotated. This cam is rotated when the clutch associated therewith is engaged. A desired shedding motion of the heald frames is therefore produced by a selectively engaging the clutches in a predetermined sequence.

To enable the clutched to be engaged in such a sequence the dobby is controlled by an electrical circuit shown in FIG. 4. This circuit includes a program reader or selector unit 26 provided with eight normally open program switches i to i which automatically return to an open position after being made. Each of these program switches is connected to an individual line j each leading one of eight relays k to k in a relay unit 28. In each relay are three contacts 30, 32 and 34. When the relay is energized contacts 30, 32 are rapidly made but contact 34 is arranged to open with delayed action. When the relay is deenergized contacts 30, 32 break and contact 34 makes. A pair of limit switches 38, 40 are in series with relay k and similar pairs of limit switches are provided in series with the other relays. When a pair of contacts 30, 32 are made a circuit comprising lines 42, 44 to a coil 1, l 2, F, 1, 1 ,1, 1" r I" is made, and provided a cam operated control switch 46 (operated by means to be described below) is also made, electrical current from a DC supply connected to a terminals 48, 50 flows through lines 52, 54 and energizes the coil. Each coil controls the operation of one of the electromagnetic clutches; for example, when the coil 1 is energized the clutch f is engaged and the cam b rotates but if the coil is deenergized then the clutch f is disengaged and the cam ceases to rotate. Similarly the coils 1 P and 1 control the operation of the clutches f, f, and 1". Likewise coils l to P I control the operation of the four clutches on the left-hand side of the loom in FIG. 1. Current to the selector unit 26 and relays k to k is supplies supplied from a DC supply connected to terminals 55, 56

Referring particularly to FIG. 1 the control switch 46 is mounted on the loom and is closed and opened once per revolution of a driven main shaft 58 by a control cam 60 mounted on the latter. Main shafts are well known in loom technology and are arranged to drive gearing controlling weft insertion and beating up motions. None of the coils I to I can under any circumstance be energized until the switch 46 is made and accordingly the shedding motion of the heald frames can only be carried out when the main shaft is in a particular angular position. Therefore the shedding motions are automatically kept in the correct sequence relative to the weft insertion and beating up operations. The eight pairs of limit switches 38, 40 (only one pair shown in FIG. 1) are mounted in the loom frame and are opened when a projection 62 mounted on each rack bar (for example the bar 14) contacts either of the switches. The switches 38, 40 are spaced apart by a distance substantially equal to the length of the stroke of the rack bar. Thus when the bar moves from right to left in FIG. 1 to raise the heald frame 4 the projection 62 opens the switch 38 when the heald frame is in substantially the fully raised position. The opening of switch 38 breaks the circuit to relay k which deenergizes to open contacts 30, 32 and accordingly coil I deenergizes to stop the shedding cam b and results in the heald frame 4 halting in substantially the raised position. When the rack bar 114 moves from left to right to lower the heald frame, the switch 38 is closed by the projection 62 and the switch 40 is opened thereby towards the end of the stroke so that the heald frame is halted in substantially the fully lowered position. The switch 40 is closed by a further right to left movement of the rack bar in the next shedding motion of the heald frame.

In FIG. 1 the program means instructing the dobby to move the heald frames in a desired predetermined sequence is a closed chain 64 of an array of pegs 66 moved successively through the selector unit 26. The pegs are arrayed at specific sections (instruction sections) along the chain length, which sections are linked together to fonn the chain and are fed individually and successively through the selector unit. Each instruction section bears instructions for the motion to be carried'out by the heald frames when that section is in the selector unit. Because there are eight heald frames then each in struction section bears eight separate instructions each disposed at a specific point across the section (i.e. across the breadth of the chain) so that an instruction concerning one heald frame is located at one specific point across the section and an instruction concerning another heald frame is located at another specific point. Each instruction is constituted by the presence or absence of a peg. The presence of a peg at a specific point indicates that the particular clutch under instruction from that point is to be engaged and the heald frame moved, when the peg is passed through the selector unit, but the absence of the peg indicates that the clutch is not to be engaged and accordingly the heald frame is to continue halted for the time being in either its raised or lowered position.

The operation of the dobby is very simple. If in the chain 64 the instruction section about to be passed through the selector unit has only one peg 66 and this peg is in the position to indicate that the clutch b is to be engaged to move the heald frame, then the absence of other pegs across the breadth of this instruction section indicates that the seven other heald frames are to remain stationary during the next immediate shedding motion. As the peg is moved through the selector unit the peg closes the switch i' and because contact 34 is at this time closed the relay k becomes energized. Contact 30, 32 are therefore immediately made in the circuit of the coil 1'. If for example, the heald frame 4 is in substantially the fully lowered position then the limit switch 40 is at this time open as a result of the previous left to right (in FIG. 1) stroke of the rack bar 114. But, because there is a time delay between the relay it" becoming energized and the breaking of contact 34 the main shaft has time to rotate the cam 60 to close the switch 46 before contact 34 breaks. Immediately switch 46 is closed the coil[ becomes energized'by current through the closed contacts 30, 32 of relay k and engages the clutch f. Drive from the motor output shaft g therefore transmitted through the clutch j to the high reduction gearbox 11 so that the shedding cam b is rotated but at a slower speed than the shaft g. Rotation of the cam b results in the rack bar moving from right to left (in FIG. 1) to close the limit switch 40 and raise the heald frame 4. The delay in breaking contact 34 is also arranged to give the rack bar time to close the open limit switch so that when contact 34 breaks current through the closed switches 38, 40 maintains the relay k energized until the moving rack bar opens the limit switch 38. Onthis occurrence relay k deenergizes to immediately open contacts 30, 32 and close contact 34. Opening contacts 30, 32 deenergize coil 1 which causes the clutch f to disengage the rotation of the shedding cam b therefore ceases. The heald frame is thus halted in substantially the fully raised position to allow for weft insertion and beating up.

The speed of movement of the rack bar is such that immediately after the limit switch is opened the main shaft 58 will by this time have rotated sufficiently in the direction of the arrow y for the cam 60 to open the switch 46. It is at this stage that the next instruction section in the chain 64 is moved into the selector unit 26 and if only one peg is again in the new section in a similar position relative to the chain breadth as the previous peg then the program switch i l is again closed and program switches F to 1' remain open. Relay k is again energized by reason that the slow opening contact 34 is still closed. Contacts 32, 34 are made and when the cam 60 is rotated to close the switch 46 the coil I is energized to engage the clutch f. The shedding earn [2 is rotated again in the same direction as previous to move the rack bar M from left to right in FIG. l to lower the heald frame 4. This movement of the rack bar closed the limit switch 38 to so that the relay k remains energized by current through closed switches 38, 40 when the delayed action contact 34 opens. Further left to right movement by the rack bar 14 opens the switch 40, and the relay k deenergizes. The opening of the contacts 30, 32 deenergizes the coil l thereby disengaging the clutch f to stop the shedding cam b and haltthe heald frame in a substantially fully lowered position whilst the switch 46 is again opened by rotation of the main shaft and further weft insertion and heating up operation take place. The operation of the dobby continues when further instruction sections of the chain 64 are passed through the selector unit 26 to operate desired program switches so as to raise or lower desired heald frames in the desired shedding sequence.

Although in the above description only one heald frame is moved during the two shedding motions described, it should be understood that if desired two or more heald frames can be moved, simultaneously during each shedding motion.

In FIG. 2 a selector unit 26 has eight program switches arranged to operate in response to instructions in the form of a chain of punched cards or punched taps 64 to control the shedding motion of the heald frames by selectively engaging any or all clutches in a desired predetermined sequence.

In an alternative embodiment the program switches i to i can be operated by pegs arrayed on the periphery of a rotating drum in a pattern designed to operate the switches in a predetermined sequence to give the desired shedding motion.

Preferably each of the shedding cams is of large diameter, for example of the order of 30 inches, so that any over run after the clutch has been disengaged will not move the heald frame very far out of the fully raised or fully lowered position.

If desired each of the gearboxes can be provided with a brake such as shown at 70 in FIGS. 1 and 3. These brakes are electromagnetically operated by the coils I l to I. For example, the brake in the gearbox d is controlled'by the coil 1 so that when the coil is energized to engage the clutch f the brake is released but when the coil is deenergized to disengage the clutch then the brake is applied to arrest the movement of the shedding cam b and the heald frame.

I claim:

1. A dobby for a heavy duty weaving loom comprising a plurality of heald frames mounted to be selectively raised and lowered; a separate motion transmitting linkage connected to each heald frame; a plurality of rotatable shedding cams operably connected to actuate respective linkages; motor means for driving said cams; torque transmission means between said motor means and each said cam comprising a motor driven shaft, a high reduction gear unit between each said shaft and the associated cam, and an electromagnetic clutch between each said shaft and the associated gear unit; and electrical means for automaticallyactuating said clutches in predetermined sequence.

2. A dobby as claimed in claim 1, wherein said electrical means for automatically actuating said clutches comprises electrical programming means consisting essentially of electrical circuit means adapted to be actuated by program means operatively connected thereto.

3. A dobby as claimed in claim 2, each said heald frame being movable by rotation of a shedding cam during engagement of the associated clutch in response to an engage clutch instruction from said program means, and means in said electrical means operable by shedding movement of the heald frame to automatically disengage the clutch to halt the heald frame in each substantially raised and lowered position and hold the clutch disengaged until said electrical means receives a further engage clutch instruction from said program means.

4. A dobby as claimed in claim 1, in which said electrical means comprises a first circuit connectable to a source of electrical current, said first circuit including a program reader provided with a program switch makable ,in response to the presence of an engage clutch instruction and breakable in response to the absence of such an instruction. the first circuit including electrically energizable relay means in series with the program switch contact means operable by the relay means and being makable by the energized relay ma means and breakable on the relay means deenergizing, limit switch means provided in series with the relay means, the limit switch means being breakable by movement of said linkage towards both the end of the heald frame lifting movement and towards the end of the heald frame lowering movement, said contact means being in series with an electrically energizable coil in a second circuit connectable to a second source of electrical current, and the clutch being engageable in response to energizing of the coil on the contact means making and disengaging in response to deenergizing of the coil on the contact means breaking in response to the deenergizing of the relay means by breaking of the limit switch means.

5. A dobby as claimed in claim 4, in which said second circuit is provided withmakeable and breakable control switch means in series with the coil, and disposed between said coil and the second source of electrical current, said control switch means being operatively made and broken by a power driven rotatable cam in the loom.

6. A dobby as claimed in claim 1 in which said motor means comprises a plurality of electric motors.

7. A dobby as claimed in claim 6 in which each motor of said motor means has first and second output drive shafts connected to first and second tor ue transmission means respectively driving mounted first an second shedding cams operatively acting on first and second heald frames respectively through first and second linkages.

8. A dobby as claimed in claim 2 in which said program means is a chain of pegs movable through a selector unit, each engage clutch instruction being constituted by a peg, and the pegs being arrayed in a predetermined pattern to produce the desired shedding motion by movement of the heald frames in a desired predetermined sequence.

9. A dobby as claimed in claim 1, in which said torque transmission means is provided with braking means selectively applicable by the electrical means to arrest rotation of a shedding cam upon the said electrical means disengaging the associated clutch, and the said braking means being releasable by the electrical means to permit rotation of the cam upon the electrical means engaging said clutch. 

1. A dobby for a heavy duty weaving loom comprising a plurality of heald frames mounted to be selectively raised and lowered; a separate motion transmitting linkage connected to each heald frame; a plurality of rotatable shedding cams operably connected to actuate respective linkages; motor means for driving said cams; torque transmission means between said motor means and each said cam comprising a motor driven shaft, a high reduction gear unit between each said shaft and the associated cam, and an electromagnetic clutch between each said shaft and the associated gear unit; and electrical means for automatically actuating said clutches in predetermined sequence.
 2. A dobby as claimed in claim 1, wherein said electrical means for automatically actuating said clutches comprises electrical programming means consisting essentially of electrical circuit means adapted to be actuated by program means operatively connected thereto.
 3. A dobby as claimed in claim 2, each said heald frame being movable by rotation of a shedding cam during engagement of the associated clutch in response to an engage clutch instruction from said program means, and means in said electrical means operable by shedding movement of the heald frame to automatically disengage the clutch to halt the heald frame in each substantially raised and lowered position and hold the clutch disengaged until said electrical means receives a further engage clutch instruction from said program means.
 4. A dobby as claimed in claim 1, in which said electrical means comprises a first circuit connectable to a source of electrical current, said first circuit including a program reader provided with a program switch makable in response to the presence of an engage clutch instruction and breakable in response to the absence of such an instruction, the first circuit including electrically energizable relay means in series with the program switch contact means operable by the relay means and being makable by the energized relay ma means and breakable on the relay means deenergizing, limit switch means provided in series with the relay means, the limit switch means being breakable by movement of said linkage towards both the end of the heald frame lifting movement and towards the end of the heald frame lowering movement, said contact means being in series with an electrically energizable coil in a second circuit connectable to a second source of electrical current, and the clutch being engageable in response to energizing of the coil on the contact means making and disengaging in response to deenergizing of the coil on the contact means breaking in response to the deenergizing of the relay means by breaking of the limit switch means.
 5. A dobby as claimed in claim 4, in which said second circuit is provided with makeable and breakable control switch means in series with the coil, and disposed between said coil and the second source of electrical current, said control switch means being operatively made and broken by a power driven rotatable cam in the loom.
 6. A dobby as claimed in claim 1 in which said motor means comprises a plurality of electric motors.
 7. A dobby as claimed in claim 6 in which each motor of said motor means has first and second output drive shafts connected to first and second torque transmission means respectively driving mounted first and second shedding cams operatively acting on first and second heald frames respectively through first and second linkages.
 8. A dobby as claimed in claim 2 in which said program means is a chain of pegs movable through a selector unit, each engage clutch instruction being constituted By a peg, and the pegs being arrayed in a predetermined pattern to produce the desired shedding motion by movement of the heald frames in a desired predetermined sequence.
 9. A dobby as claimed in claim 1, in which said torque transmission means is provided with braking means selectively applicable by the electrical means to arrest rotation of a shedding cam upon the said electrical means disengaging the associated clutch, and the said braking means being releasable by the electrical means to permit rotation of the cam upon the electrical means engaging said clutch. 